The International Whaling Commission (IWC) has rejected a Brazilian proposal to create a Whale Sanctuary in the Southern Atlantic.
Meanwhile, Japan continued to push for the IWC to lift a 32-year whaling ban.
During voting, 39 of the 67 participating countries backed the Brazilian proposal at the annual IWC meeting in the Brazilian city of Florianopolis, according to non-governmental organisations campaigning for whale conservation.
They included Argentina, South Africa, the European Union and Switzerland.
However, their votes were not enough to secure the three-quarters majority needed for the proposal to pass.
But 25 countries voted against the sanctuary, including Japan, Norway and Iceland, the only countries that currently hunt whales in defiance of the IWC ban.
Three countries abstained in the vote.
Japan has proposed changing the required majority from three-quarters to a simple majority, in the hope that this will ease the passage of its own proposal to allow commercial whaling, according to the environmental organisation Pro Wildlife.
Japan wants the IWC to set sustainable limits for hunting whale species that it says are abundant.
The IWC agreed to a moratorium on commercial whaling in 1986 to protect whale populations on the brink of extinction.
Japan kills about 450 whales annually, according to Pro Wildlife.
It justifies the practice by saying it is necessary to evaluate whale populations for scientific purposes, but the whale meat ends up at restaurants and supermarkets.
Norway and Iceland, which have formally objected to the moratorium, kill up to 700 and about 200 whales respectively every year.
The meeting will run until Friday.